All military-style semi-automatic rifles are being banned.

The ban will also cover all assault rifles, high capacity magazine and parts that can convert a semi-automatic weapon to a military-style semi-automatic firearm.

The Prime Minister says, in short, every semi-automatic weapon used in the terrorist attack on Friday will be banned in this country.

And Jacinda Ardern says it will happen immediately, with her Government implementing a measure to stop the weapons being sold until the new laws can be implemented.

Newstalk ZB political editor Barry Soper told Andrew Dickens he thought the decision from the government was the right one and will have strong public support.

"This is a tougher stance than many people expected but I totally agree they should be outlawed. It's not just because of the horrible events last Friday. For the last 25 years, they have grappled about doing something with these weapons."

National says it will support the changes announced by the Prime Minister.

Leader Simon Bridges says the public doesn’t need access to military-style semi-automatic weapons.

He says National supports them being banned along with assault rifles - and says his party will work constructively with the government to get the changes through.

The law to be in place within three weeks.